The thing that is new and different now is that basically for the last 50 years of biomedical research, we’ve worked only on nonhuman systems: yeast, fruit flies, worms, mice. Stem cells are a tool that can be applied to human systems. We’re at the beginning of a process that will truly crack open human cell biology and physiology.

QUESTION: There is a lot of talk about stem cells leading to possible treatments, even cures, for many difficult diseases and conditions. Does such talk concern you? Is it hyperbole? Are people’s expectations too great?

ANSWER: Of course, I’m worried about it. No scientist wants to make unrealistic projections. On other hand, you can’t look at stem cells and not see the enormous potential. I think what’s lost is not the potential, but the sense of time.

Things are changing fast. Some of the things we do now were science fiction when I was an undergrad at UCSD 30 years ago. But it’s still progress measured in terms of years and decades. There’s a kind of disconnect in expectations. How long does it take to achieve a real breakthrough? To actually solve a disease? There’s no way to make that prediction. Research is about discovering what you don’t know. You can discover something that makes the research go faster or something that makes it go slower. Breakthroughs and setbacks happen constantly. If you look across the whole spectrum of effort, there is some pretty amazing progress happening almost every day, but it isn’t always happening where you most want it.

QUESTION: When people discuss or debate stem cell research, often they’re talking about human embryonic stem cells (ESC), which are controversial for some because they are derived from early-stage human embryos. ESCs have the ability to become many different kinds of cell. Does that make them the gold standard? Can they be replaced by other kinds of stem cells?

ANSWER: I don’t think anybody knows yet. Again, it’s an issue of research: We’ve got to do the work and figure it out. But the question can be addressed another way. Imagine for a moment that there were no ethical issues raised regarding embryonic stem cells. If there weren’t, they would simply be an important tool in the toolbox, but not the only tool.

Right now, they are clearly much better understood than other kinds of cells. People have been looking at them longer. And they definitely have special, unique properties. But whether this will be true three years from now, who knows.

QUESTION: Do you have pet peeves regarding how the public perceives stem cell research?

ANSWER: I have a few.

The first is the myth that human embryonic stem cells come from aborted fetuses. This is nonsense. It’s just not true. These stem cells come from frozen blastocysts (a very early embryo consisting of 150-300 cells) not used in in-vitro fertilization procedures. These cells are going to be discarded, no matter what. End of story. There’s no abortion involved.

Second, people sometimes think stem cell research is just one thing. In fact, the research covers lots of different kinds of stem cells with different properties related to different diseases. No one kind of stem cell can substitute for another. What makes ESCs so special is they can make many kinds of stem cells that we can’t otherwise get in reasonable qualities.